My save file is all about world-building. It's a world where occults live out in the open and have their own, unique cultures. (Spellcasters have a school and a religious leader, Orcs live in tribes, many lots are built with "panic rooms" to accommodate werewolves, etc.) There are tons of long-running families, each with their own theme and place in society. There are tons of intricate societal rules and quirks I make my sims follow, unique holidays for each occult, and drama. Just recently, I capped off a plot that's been running for about 4~ IRL years, about an evil spellcaster who stays immortal by possessing the body of his descendants.
I play every family, but my main family are the Stellars. They're a spellcaster family who don't have a concrete theme compared to most families, since I like to change things up. But unlike most spellcasters, they're more willing to marry outside their life state. The current religious leader is one of their ancestors, and that's a whole bit of drama because he had to execute the current heir's dad for plot-related reasons, it's this whole thing.